1. Field of the Invention
This invention relates to a telescopic support, and in particular concerns a telescopic support for holding and/or manipulating a medical device.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
There are several applications in which a drive is used to maneuver a carrier around a fixed point. An example of such an application is a robotic arrangement to hold a camera for use in endoscopy, where the endoscope is inserted into an incision in the body of a patient, and is then driven to move along or around two or more axes in such a way that the movement is confocal around the incision. This means that the endoscope may be moved with the point of the incision being the center of motion, so that the endoscope remains inserted into the incision and does not exert any substantial forces on the sides of the incision.
Confocal motion of this type often comprises pan, tilt, and zoom motions. During the “tilt” movement, the angle of the endoscope changes with respect to the surface of the patient's skin in which the incision is made.
In order to achieve tilt motion without exerting forces on the sides of the incision in the patient's body, an arcuate arm may be provided, having a radius of curvature which is centered on the incision. The endoscope is typically carried at one end of the arcuate arm, and it will be appreciated that driving the arcuate arm to describe a rotary motion about the incision, with all parts of the arm remaining at the same distance from the incision, causes the endoscope to tilt with respect to the patient, whilst remaining substantially motionless at the point where the endoscope passes through the incision.
Depending upon the application for which the endoscope is being used, however, the range of tilt motion that is required of the endoscope may be relatively large. To accommodate the positions of the endoscope that are required in various surgical operations, an endoscope may be required to be positioned in a substantially vertical orientation (i.e. perpendicular to the skin of the patient in which the incision is made), to a position which is a few degrees below horizontal (i.e. below the plane of the patient's skin in which the incision is made). In total, it is desirable for the endoscope to have a range of motion of around 110°.
If a solid arcuate arm is used however, it will be understood that this arcuate arm must cover at least 110° of arc in order to be able to support the endoscope in both of these end-of-range positions. This raises difficulties since, if the endoscope is moved to a substantially vertical position, the far end of the arcuate arm (i.e. the end furthest from the point at which the endoscope is supported) would travel sufficiently far along its arcuate path to press into the skin of the patient. Clearly, this is undesirable.
It is an object of the present invention to seek to ameliorate this difficulty.